Morphological adaptation and evolution of multiporous placoid sensilla in female Agaonids (Chalcidoidea, Hymenotera)
Author of the article:LI Zong-Bo1** YANG Pei2 ZHAO Jian1 YANG Da-Rong2***
Author's Workplace：1. Key Laboratory of Forest Disaster Warning and Control in Yunnan, College of Forestry, Southwest Forestry University, Kunming 650224, China; 2. Xishuangbanna Tropical Botanical Garden, Chinese Academy of Sciences, Kunming 650223, China
Key Words：Agaonidae, female wasp, multiporous placoid sensilla, morphology, evolution
Abstract： [Objectives] To describe the ultramorphology of the multiporous placoid sensilla (MPS) located on the antennae of female Agaonids (Chalcidoidea: Agaonidae) and discuss the morphological adaptation and evolution of these organs in the context of the phylogeny of the Agaonidae. [Methods] The morphology, density and distribution of MPS in females of 70 species from 12 genera of the Agaonidae were observed by SEM. [Results] There are 3 types of MPS on the antennae of female Agaonids: elongated multiporous placoid sensilla (MPS-E), chaetica multiporous placoid sensilla (MPS-C) and rounded multiporous placoid sensilla (MPS-R). MPS-E can have either a single whorl arrangement (TypeⅠ) or a multiple whorl arrangement (TypeⅡ). MPS-C also have two distinct arrangements; lateral arrangement (Type Ⅲ) and socket situated, axial arrangement (Type Ⅳ). MPS-R only occur on the third club on the ventral surface of antennae in the genera Eupristina, Ceratosolen, Waterstoniella, Tetrapus. Although all 4 different arrangements increase MPS receptor surface area by lengthening and increasing the number of sensilla, branching is the key way of improving sensillar sensitivity. On the other hand, numbers of MPS were positively correlated to fig diameter (r=0.249, P=0.003), but branching was negatively correlated to fig diameter (r=－0.231, P=0.017). [Conclusion] The antennae of female Agonids have 3 types of MPS; MPS-E, MPS-C and MPS-R. Elongation and branching of MPS were typical morphological adaptations the repeated evolution of which may help female agaonids to effectively locate species-specific compounds of female floral figs in complex rainforest.